Egypt's highest court ruled on Sunday that the electoral law used to elect the upper house of parliament, known as the Shura Council, was "unconstitutional", dpa reported.
The Constitutional Court also ruled that the constituent assembly, which drafted Egypt's current constitution, was invalid. The assembly's remit ended after the constitution was approved in a referendum in December.
The Shura Council, which used to have limited powers, is currently holding the legislative powers, until the election of the lower chamber.
It is unclear whether the decision will lead to dissolving the Shura council.
The Shura council elections were held under the same law of the lower house, which was disbanded by the former ruling Supreme Council of the Armed Forces in June 2012 after the court deemed the law "unconstitutional."